Vibrational analysis of d-PCL(530)/siloxane based hybrids doped with two lithium salts

Published online: 22 May 2013The present study has been focused on environmentally friendly sol-gel derived electrolytes based on a di-urethane cross-linked d-PCL(530)/siloxane network (where d represents di, PCL identifies the poly(ε–caprolactone) biopolymer and 530 is the average molecular weight in g.mol-1) doped with a wide range of concentration of lithium perchlorate (LiClO4) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). Fourier Transform Infrared and Raman (FT-IR and FT-Raman, respectively) spectroscopies have been applied to evaluate the extent of ionic association. Characteristic bands of the PCL(530) segments, of the urethane cross-links and of the anions have been examined to gain insight into the cation/biopolymer, cation/anion and cation/cross-link interactions. In both electrolyte systems “free” ions and contact ions have been identified. The addition of salt modifies the hydrogen-bonded array of the host matrix, causing the destruction/formation of the urethane/urethane aggregates.Fundação para a Ciência e a Tecnologia (FCT

Applications of hybrid organic-inorganic nanocomposites

Organic - inorganic hybrid materials do not represent only a creative alternative to design new materials and compounds for academic research, but their improved or unusual features allow the development of innovative industrial applications. Nowadays, most of the hybrid materials that have already entered the market are synthesised and processed by using conventional soft chemistry based routes developed in the eighties. These processes are based on: a) the copolymerisation of functional organosilanes, macromonomers, and metal alkoxides, b) the encapsulation of organic components within sol - gel derived silica or metallic oxides, c) the organic functionalisation of nanofillers, nanoclays or other compounds with lamellar structures, etc. The chemical strategies (self-assembly, nanobuilding block approaches, hybrid MOF ( Metal Organic Frameworks), integrative synthesis, coupled processes, bio-inspired strategies, etc.) offered nowadays by academic research allow, through an intelligent tuned coding, the development of a new vectorial chemistry, able to direct the assembling of a large variety of structurally well defined nano-objects into complex hybrid architectures hierarchically organised in terms of structure and functions. Looking to the future, there is no doubt that these new generations of hybrid materials, born from the very fruitful activities in this research field, will open a land of promising applications in many areas: optics, electronics, ionics, mechanics, energy, environment, biology, medicine for example as membranes and separation devices, functional smart coatings, fuel and solar cells, catalysts, sensors, etc

Applications of advanced hybrid organic-inorganic nanomaterials: From laboratory to market

Today cross-cutting approaches, where molecular engineering and clever processing are synergistically coupled, allow the chemist to tailor complex hybrid systems of various shapes with perfect mastery at different size scales, composition, functionality, and morphology. Hybrid materials with organic-inorganic or bio-inorganic character represent not only a new field of basic research but also, via their remarkable new properties and multifunctional nature, hybrids offer prospects for many new applications in extremely diverse fields. The description and discussion of the major applications of hybrid inorganic-organic (or biologic) materials are the major topic of this critical review. Indeed, today the very large set of accessible hybrid materials span a wide spectrum of properties which yield the emergence of innovative industrial applications in various domains such as optics, micro-electronics, transportation, health, energy, housing, and the environment among others (526 references)

Stromatolites as Biosignatures of Atmospheric Oxygenation:Carbonate Biomineralization and UV-C Resilience in a Geitlerinema sp. - Dominated Culture

Modern stromatolites are key to the record of past microbial activity preserved in fossil carbonate deposits. Mono-phototrophic cultures dominated by the cyanobacterium Geitlerinema sp. were obtained from a laboratory-maintained, low magnesium-calcite stromatolite originating from Lagoa Vermelha, Brazil. This lagoonal system has been described as a Precambrian analog, illustrating a period of photosynthetically induced atmospheric oxygenation, which created a global sanctuary from shortwave solar radiation and enabled the evolution of modern life on Earth. The enrichment cultures precipitate carbonates in minimal media, suggesting that cyanobacterial photosynthesis and extracellular polymeric substance production may be crucial in the mineralization of the studied stromatolite. We further show that Geitlerinema sp. can build and maintain filamentous mats under long-term UV-C exposure. Our results suggest that present day stromatolites dominated by cyanobacteria may be interpreted as biosignatures of atmospheric oxygenation and have implications for the search for putative biological traces on Mars

ORMOCER's, inorganic-organic polymer materials for applications in micro systems technology

Due to the unesthetic appearance, the toxicologigal problems of mercury and the galvanic corrision there is a need for a posterior dental filling material which is able to substitute the amalgam fillings. To provide such materials mulifunktional urethane- and thioether oligo (meth)acrylate alkoxysilanes as sol-gel precursors have been used for preparation of a special family of inorganic/organic copolymer composites (ORMOCER s) on a molecular scale.The alkoysilyl groups of the silane allow the formation of inorganic Si-O-Si-network by hydrolysis and polycondensation reactions. In order to achieve X-ray-opacity higher than that of dental enamel silicon can partly be replaced by heavier elements,e.g. zirconium. After incorporation of special dental glass fillers the resulting paste-like composite can be applied by the dentist. Beside the UV- and thermally induced polymersation a light- and redox-induced curing is also possible to build up the additional organic polymer structure. Toxicol ogical problems are not exspected because of the usage of silane-connected acrylates and methacrylates and therefore the linkage to the inorganic polymer structure

Verfahren zur Herstellung von Styryl-funktionalisierten Silanen

DE 10159859 C UPAB: 20030303 NOVELTY - Production of styryl-substituted silanes comprises: (i) reacting a ring-halogenated styrene in a solvent mixture of diethyl ether and tetrahydrofuran in 30:70 to 70:30 ratio by volume with magnesium, so that the reaction temperature does not exceed the boiling temperature of the mixture at room pressure; and (ii) reacting the resultant Grignard reagent with a silane in a solvent mixture of diethyl ether and tetrahydrofuran at not more than 20 deg. C. DETAILED DESCRIPTION - Production of styryl-substituted silanes of formula (St)bSiR'aR4-a-b (I) comprises: (i) reacting a ring-halogenated styrene of formula StX (II) in a solvent mixture of diethyl ether and tetrahydrofuran (THF) in 30:70 to 70:30 ratio by volume with magnesium, so that the reaction temperature does not exceed the boiling temperature of the mixture at room pressure; and (ii) reacting the resultant Grignard reagent with a silane of formula SiR'aR3-a (III) in a solvent mixture of and THF at not more than 20 deg. C: St = optionally substituted styryl; R = a group bound to silicon by a carbon atom; R' = optionally substituted 1-12C alkoxy; a = 0, 1, 2 or 3; b = 1, 2 or 3; X = halogen bound to the phenyl ring of the styryl group USE - Styryl-functionalized alkoxysilanes are used in organic polymerizable silicate polycondensates useful for producing e.g. pigment particles, oxygen-permeable membranes or electrophotographic materials. ADVANTAGE - The present method is simple and gives much better yields than existing methods of preparing styryl-functionalized alkoxysilanes